A. Field of the Invention
The field of the present invention relates generally to conveyor belt systems configured for carrying bulk materials thereon. More particularly, the present invention relates to belt scraper assemblies used with such systems to remove unwanted materials from the surface of the conveyor belt. Even more particularly, the present invention relates to such conveyor belt scraper assemblies that are self-adjusting and which are configured to allow replacement of worn components without stopping the conveyor belt system.
B. Background
Continuous belt conveyor systems are commonly utilized to carry bulk materials, including trash, recyclables, gravel, coal, aggregate and many other types of materials, from one location to another, sometimes over long distances. One well known configuration for such conveyor systems has a continuous belt that comprises an upper flight section which carries the bulk materials to a location where it is dumped off the end of the conveyor belt for disposal or further processing and a lower flight section that returns the belt to a position where it can receive more bulk materials. A supporting framework supports roller assemblies, placed at appropriate intervals, over which the generally flexible belt travels in the upper and lower flight sections. To better maintain the bulk materials on the belt when traveling through the upper flight section, it is common to arrange the roller assemblies in the upper flight section in a generally trough or trough-like cross section that supports the belt in a corresponding configuration. These roller assemblies are commonly referred to as trough roller assemblies. The lower flight section is typically supported by return roller assemblies comprising a single roller that supports the flexible belt in a generally flat or horizontal configuration.
The carrying surface of the conveyor belt, which contacts the return roller assemblies in the lower flight section, typically becomes covered or coated with abrasive and/or corrosive debris from the materials carried by the conveyor belt system. As well known in the industry, the debris on the carrying surface of the conveyor belt is likely to damage the return roller assemblies, thereby creating jagged or sharp edges on its rolling surfaces that will in turn cut into the conveyor belt. Replacing the conveyor belt in such systems is expensive and results in substantial system downtime, which can be even more expensive for the conveyor belt system operator than the cost of the belt. In addition, the debris on the surface of the conveyor belt can damage the conveyor belt system equipment by getting into the bearings of the return roller assemblies and/or falling into other operational equipment that is used to operate the system. This debris can also fall on to the floor and create operational and safety issues for the system operator. To avoid these problems, most conveyor belt systems utilize one or more belt scrapers to scrape the debris off of the carrying surface of the conveyor belt, typically while on its return flight in the lower flight section, while it is moving.
The present invention is directed to an improved belt scraper assembly for use with conveyor belt systems to clean the carrying surface of the conveyor belt. The prior art belt scrapers generally attach to the supporting framework in a manner that directs the scraper blade up against the downward facing carrying surface of the conveyor belt. Unfortunately, the way in which the prior art belt scrapers attach and operate make replacement of worn or damaged scraper blades very difficult. In addition, the prior art belt scrapers have a somewhat complicated configuration that makes them more expensive, difficult to use and likely to breakdown, particularly due to the debris from materials carried by the conveyor belt system. An additional well known problem with prior art belt scrapers is that they typically require the conveyor belt system to be stopped for a period of time in order to replace the scraper blade, which results in downtime for the conveyor belt system operator. Yet another problem with most prior art belt scrapers is that they are not self-adjusting, meaning that they do not compensate for wear of the scraper blade over time. Because scraper blades are preferably made out of materials that are softer than the conveyor belt to reduce wear on the conveyor belt, without some type of self-adjusting feature the scraper blade will separate from the surface of the conveyor belt as it wears down due to the movement of the conveyor belt and the debris. To avoid this problem, some prior art belt scraper assemblies utilize metal or other hard materials for the scraper blade. Unfortunately, this increases the risk of damage to the conveyor belt.
Several prior art patents address some of the problems associated with belt scrapers. For instance, U.S. Pat. No. 4,541,523 to Stockton discloses a conveyor belt scraper that has a track arrangement positioned below the conveyor belt, a carriage that slidably engages the track arrangement, a locking mechanism that locks the carriage to the track arrangement, a plurality of aligned scraper blade assemblies and at least one coil spring arrangement connecting the scraper blade assemblies to the carriage so as to bias the blades against the surface of the conveyor belt against the direction of belt travel. The scraper includes a counterweight that biases the blades against the conveyor belt in a manner that is configured to compensate for wear of the blades. U.S. Pat. No. 4,787,500 to Holz discloses a conveyor belt scraper having a scraper element that is slidably received in a mounting plate disposed below the conveyor belt with a biasing mechanism below the mounting plate to bias the elastomeric blade portion of the scraper element against the downward facing surface of the conveyor belt. The biasing mechanism compensates for blade wear and the use of slidably received scraper elements is configured to allow replacement of the scraper elements without shutting down the conveyor belt.
Despite the advancements offered by the prior art patents, what is needed is an improved configuration for a conveyor belt scraper assembly that is configured to effectively scrape debris off of the carrying surface of a moving conveyor belt. The preferred belt scraper assembly is configured to scrape debris off the downward facing carrying surface in the lower flight section of a continuous belt conveyor system. Preferably, the belt scraper assembly should enable the operator to simply and quickly replace the worn scraper blade without having to stop the conveyor belt system. The preferred belt scraper assembly should utilize a scraper blade that is softer than the conveyor belt, to reduce risk of damage to the conveyor belt, and effectively compensate for wear of the scraper blade so as to maintain its scraping effectiveness. Preferably the belt scraper assembly should more efficiently utilize the scraper blade materials so as to reduce the frequency of having to replace the scraper blade. The preferred scraper belt assembly should be relatively inexpensive and simple to install and easy to operate.